Avascular Necrosis Avascular necrosis (AVN) is a disease of the bone. Necrosis is a general term that means a cell has died. AVN is also called:
- Aseptic necrosis
- Ischemic bone necrosis
- Bone infarction
Grades of AVN There are four stages that define how bad the disease has progressed.
- Stage 1 - has a normal x-rays but MRI reveals the dead bone.
- Stage 2 - can be seen on regular x-ray but there is no collapse of the femoral ball.
- Stage 3- shows signs of collapse.
- Stage 4 - has collapse on x-ray and signs of cartilage
Osteonecrosis of the hip develops when the blood supply to the femoral head is disrupted. Without adequate nourishment, the bone in the head of the femur dies and gradually collapses.
- Blood vessels can be damaged even due to the injury to the hip itself.
- Damage to blood vessels can also occur due to fracture of femoral neck.
- Hip dislocation can also cause damage to blood vessels.
- Taking high doses of corticosteroids for a long time, such as prednisone or cortisone, because they can increase fatty substances (lipids) in the blood, which can block arteries
- Smoking and alcohol consumption have been found to cause avascular necrosis. Smoking leads to constriction of blood vessels, thereby reducing the blood flow to hip joint.
- Childhood diseases including Legg-Calve Perthes disease
- Chemotherapy or Radiation